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1.
Claudia Raedig Carsten F. Dormann Anke Hildebrandt Sven Lautenbach 《Biodiversity and Conservation》2010,19(6):1523-1546
Monographic data rely on specimens deposited in herbaria and museums, which have been thoroughly revised by experts. However,
monographic data have been rarely used to map species richness at large scale, mainly because of the difficulties caused by
spatially heterogeneous sampling effort. In this paper we estimate patterns of species richness and narrow endemism, based
on monographic data of 4,055 Neotropical angiosperm species. We propose a geometric interpolation method to derive species
ranges at a 1° grid resolution. To this we apply an inverse distance-weighted summation scheme to derive maps of species richness
and endemism. In the latter we also adjust for heterogeneous sampling effort. Finally, we test the robustness of the interpolated
species ranges and derived species richness by applying the same method but using a leave-one-out-cross-validation (LOOCV).
The derived map shows four distinct regions of elevated species richness: (1) Central America, (2) the Northern Andes, (3)
Amazonia and (4) the Brazilian Atlantic coast (‘Mata Atlantica’). The region with the highest estimated species richness is
Amazonia, with Central America following closely behind. Centers of narrow endemism are located over the entire Neotropics,
several of them coinciding with regions of elevated species richness. Sampling effort has a minor influence on the interpolation
of overall species richness, but it substantially influences the estimation of regions of narrow endemism. Thus, in order
to improve maps of narrow endemism and resulting conservation efforts, more collection and identification activity is required. 相似文献
2.
3.
The mechanisms controlling early adenovirus gene expression in vivo have been studied using inhibitors of protein synthesis. When inhibitors were added shortly before or at the onset of infection, viral mRNA from all early regions was transcribed, spliced and accumulated over a 7 hr period. After longer pretreatment, accumulation of several early mRNAs were suppressed. Addition of inhibitors 1 hr after infection enhanced the accumulation of viral mRNA in the cytoplasm. Translation of early mRNA selected on adenovirus DNA in a cell-free system reflected the amount of viral mRNA present. A viral coded product may therefore control accumulation of viral mRNA.A different pattern emerged when inhibitors of protein synthesis were removed at 5 hr postinfection and cells were pulse-labeled in vivo. If inhibitors were introduced at or before infection, early viral proteins were synthesized only after a lag of 1–3 hr. However, if treatment was introduced 1 hr post-infection, reversion of the protein synthesis block was instantaneous. It appears that protein synthesis inhibitors reveal an in vivo translational block for viral mRNA. This block could be overcome by preinfection with a related virus. Furthermore, no block was observed in a virus-transformed human embryonic kidney cell line (293) which expresses early region 1 of the viral genome. Viral gene product(s) encoded in early region 1 may control translation of early adenovirus messenger RNA in vivo. 相似文献
4.
Sven Skog Viola Eriksson Eva Eliasson 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,672(1):33-44
Suspension cultures of ‘Chang liver’ cells were synchronized by preincubation in a glutamine-deficient medium or by thymidine blockade. Specific arginase activity varied in the synchronized cultures, being high when the number of S-phase cells was maximal. A relationship between high arginase activity and a high percentage of (S+G2) cells was also found when unsynchronized cells were separated by velocity sedimentation. The increase in arginase activity near the G1/S border was totally inhibited in the presence of cycloheximide. The rate of decrease in activity after addition of the drug indicated that the variations in the rate of synthesis of the enzyme, while the rate of degradation was more or less constant, corresponding to 4–6% per h. The role of arginase in cells lacking a urea cycle and the regulation of arginase activity in ‘Chang liver’ cells is discussed. 相似文献
5.
Ulrich Weser Karl-Heinz Sellinger Edmund Lengfelder Walther Werner Joachim Strähle 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,631(2):232-245
The copper complex of indomethacin (1-(p-chlorobenzoyl)-5-methoxy-2-methyl-indole acetate), a common anti-inflammatory drug, was prepared and characterized. Crystal structure determination revealed the dimeric form of the 1:2 complex, namely Cu2(indomethacin)4 · L2, in the unit cell. Suprisingly, the copper-copper distance (263 pm) was very close to metallic copper (256 pm). The two coordination sites in the copper-copper axis can be readily replaced by superoxide. An intriguing similarity to Cu2(acetate)4 was seen.Due to the lipophilic nature of the indomethacin ligand, this copper complex reacted with superoxide in aprotic solvents. The superoxide dismutating activity was successfully demonstrated in Me2SO/water and acetonitrile/water mixtures using the nitro-blue tetrazolium assay and pulse radiolysis. The second-order rate constant of 6 · 109 M?1 · s?1 in strictly aqueous systems dropped only slightly to 1.1 · 109 M?1 · s?1 when aprotic solvents were used. This is the fastest rate constant ever observed for a copper-dependent dismutation of superoxide. The KO2-induced lipid peroxidation in both erythrocytes and liver microsomes was suppressed by 70% in the presence of 1 · 10?10 mol · ml?1 of Cu2(indomethacin)4. The inhibitory action dropped to 25% when Cu2Zn2superoxide dismutase was employed. The formation of copper · indomethacin in rat serum after administration of indomethacin was shown in vitro and in vivo. 相似文献
6.
DNA was efficiently and quantitatively isolated from extremely small quantities of mycelia (0.1–10 mg) of different phytopathogenic
moulds by grinding freeze-dried mycelia with glass beads and then using a commercial DNA extraction kit. The efficiency of
disruption of the mycelia and the quantitative DNA extraction was proved by microscopy and the quantification of isolated
DNA by real time PCR.
Presented at the 27th Mykotoxin-Workshop, Dortmund, Germany, June 13–15, 2005
Financial support: German Research Foundation (DFG grant Pr 708/2). J.M. thanks the Cusanuswerk for a doctoral scholarship 相似文献
7.
Ralf Heinrich Peter Bräunig Ismeni Walter Henning Schneider Edward A. Kravitz 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(7-8):617-629
In the American lobster (Homarus americanus) the biogenic amines serotonin and octopamine appear to play important and opposite roles in the regulation of aggressive behavior, in the establishment and/or maintenance of dominant and subordinate behavioral states and in the modulation of the associated postural stances and escape responses. The octopamine-containing neurosecretory neurons in the thoracic regions of the lobster ventral nerve cord fall into two morphological subgroups, the root octopamine cells, a classical neurohemal group with release regions along second thoracic roots, and the claw octopamine cells, a group that selectively innervates the claws. Cells of both subgroups have additional sets of endings within neuropil regions of ganglia of the ventral nerve cord. Octopamine neurosecretory neurons generally are silent, but when spontaneously active or when activated, they show large overshooting action potentials with prominent after-hyperpolarizations. Autoinhibition after high-frequency firing, which is also seen in other crustacean neurosecretory cells, is readily apparent in these cells. The cells show no spontaneous synaptic activity, but appear to be excited by a unitary source. Stimulation of lateral or medial giant axons, which excite serotonergic cells yielded no response in octopaminergic neurosecretory cells and no evidence for direct interactions between pairs of octopamine neurons, or between the octopaminergic and the serotonergic sets of neurosecretory neurons was found. 相似文献
8.
Risk assessment is part of the risk analysis process as it is used in veterinary medicine to estimate risks related to international trade and food safety. Data from monitoring and surveillance systems (MO&SS) are used throughout the risk assessment process for hazard identification, release assessment, exposure assessment and consequence assessment. As the quality of risk assessments depends to a large extent on the availability and quality of input data, there is a close relationship between MO&SS and risk assessment. In order to improve the quality of risk assessments, MO&SS should be designed according to minimum quality standards. Second, recent scientific developments on state-of-the-art design and analysis of surveys need to be translated into field applications and legislation. Finally, knowledge about the risk assessment process among MO&SS planners and managers should be promoted in order to assure high-quality data. 相似文献
9.
10.
F. Bylund F. Guillard S.-O. Enfors C. Trägårdh G. Larsson 《Bioprocess and biosystems engineering》1999,20(5):377-389
A large bioreactor is heterogeneous with respect to concentration gradients of substrates fed to the reactor such as oxygen and growth limiting carbon source. Gradient formation will highly depend on the fluid dynamics and mass transfer capacity of the reactor, especially in the area in which the substrate is added. In this study, some production-scale (12 m3 bioreactor) conditions of a recombinant Escherichia coli process were imitated on a laboratory scale. From the large-scale cultivations, it was shown that locally high concentration of the limiting substrate fed to the process, in this case glucose, existed at the level of the feedpoint. The large-scale process was scaled down from: (i) mixing time experiments performed in the large-scale bioreactor in order to identify and describe the oscillating environment and (ii) identification of two distinct glucose concentration zones in the reactor. An important parameter obtained from mixing time experiments was the residence time in the feed zone of about 10 seconds. The size of the feed zone was estimated to 10%. Based on these observations the scale-down reactor with two compartments was designed. It was composed of one stirred tank reactor and an aerated plug flow reactor, in which the effect of oscillating glucose concentration on biomass yield and acetate formation was studied. Results from these experiments indicated that the lower biomass yield and higher acetate formation obtained on a large scale compared to homogeneous small-scale cultivations were not directly caused by the cell response to the glucose oscillation. This was concluded since no acetate was accumulated during scale-down experiments. An explanation for the differences in results between the two reactor scales may be a secondary effect of high glucose concentration resulting in an increased glucose metabolism causing an oxygen consumption rate locally exceeding the transfer rate. The results from pulse response experiments and glucose concentration measurements, at different locations in the reactor, showed a great consistency for the two feeding/pulse positions used in the large-scale bioreactor. Furthermore, measured periodicity from mixing data agrees well with expected circulation times for each impeller volume. Conclusions are drawn concerning the design of the scale-down reactor. 相似文献